Our lab is interested in the mechanosensory signaling pathways initiated at the lov-1/PC1 and pkd-2/PC2 polycystin cation channel complex. We will exploit the nematode, C. elegans, in a series of behavioral, genetic, and biochemical experiments to elucidate the role of several novel gene products in these pathways. C. elegans males exhibit a complex mating behavior program which requires intact polycystins for two distinct steps, response to contact and location of the hermaphrodite vulva. We have recently discovered five new genes named cwp1-5, expressed exclusively in male worms in the identical set of 21 sensory neurons as the polycystins, lov-1 and pkd-2. CWP1-4 proteins contain a signal sequence at the N- terminal and are predicted to be secreted, while CWP-5 contains a transmembrane domain. Behavioral analysis of cwp mutant strains reveals strong effects on mating behavior in wild type and pkd-2 (null) males. A deletion removing both cwp-2 &cwp-3 suppresses the location of vulva defect in pkd-2(null) worms. An in- frame deletion that removes the transmembrane domain of CWP-5 causes a severe (50%) response to contact defect in wild-type worms, and further reduces the response frequency in pkd-2 (null) males from 37% to 3%. This proposal focuses on uncovering the mechanistic details of how CWPs interact with polycystins and other, alternative (as yet undescribed) mechanosensory signaling pathways. Knowledge of polycystin independent pathways for mechanosensation has great relevance for the treatment of polycystic kidney disease (PKD), in which PC1 and/or PC2 function is lost. The two specific aims dissect the mechanisms of suppression of location of vulva defects by cwp-2&cwp-3 deletion and the response to contact defect in cwp-5(mutant) males, respectively. Each aim is composed of several sub-aims, directly testing specific hypotheses about CWP interactions, localization, and function. We propose experiments that take advantage of the unique genetic tractablity of C. elegans, such as transgenesis, RNAi, and epistasis tests. We also propose a forward genetic suppressor screen to identify additional components of signaling pathways for polycystin-dependent behaviors. The experiments we propose will provide important new data regarding the transduction of mechanical stimuli into behavioral output. PKD is the most common genetic disease in the USA. Through analysis of cwp and polycystin genes, our project will aid in the understanding of how loss of the ability to sense fluid flow in the kidney leads to dysfunction in PKD. Furthermore, characterizing new pathways that allow for normal sensation in the absence of polycystin proteins might lead to new therapeutic approaches.